The study is likely the most rigorous look to date on the benefits of coffee on liver health in the U.S. It was based on data from the National Health and Nutrition Examination Survey which asked people about what they eat and drink.
“This is the closest we’re ever going to get to a linkage between what people are eating or drinking and the health of their liver, absent a longitudinal study where we set out to follow people for many, many years,” said Elliot Tapper, MD, assistant professor of gastroenterology at the University of Michigan, and the study’s senior author.
Researchers looked at data from about 4,500 patients who had participated in the survey in 2017-2018. The participants were 20 years old or older, with an average age of 48; 73% were overweight, about the national average.
The researchers found no connection between coffee consumption and a measure of fatty liver. But they found a link between coffee and liver stiffness.
Those who drank more than three cups of coffee daily had a lower liver stiffness measure measured in what’s known as kilopascals. Liver stiffness higher than 9.5 kilopascals is a sign of liver fibrosis, which can lead to cirrhosis.
Tapper said the data will be reassuring to doctors who suggest coffee-drinking to patients.
“There are hepatologists around the world who are actively recommending coffee – they’ll feel empowered by these data,” he said. “I would still like to see more … data before I start spending our precious time counseling patients about coffee. There are many other data-driven interventions for the management of liver disease that we should be focusing our time on.”
Still, he said, the data will be important for patients who are particularly interested in natural remedies.
“For patients who are very interested in a natural supplement, to feel like they’re taking an active role in the health of their liver, I will tell them to avoid carbohydrates and increase their exercise – and that it is OK to add coffee to their daily routine.”
A study based on a United Kingdom database found that coffee appeared to protect against chronic liver disease, said Nathan Davies, PhD, professor of biochemistry at the Institute of the Liver and Digestive Health at the University College London.
“Looking at a snapshot moment does not necessarily reflect an individual’s behavior during the onset and development of their condition,” Davies said. “As such, there are a number of behavioral and nutritional factors that could be contributing to the observed effect over a period of years.”
He pointed out that while different coffee and brewing types affect the amount of caffeine in a cup, all cups of coffee in this study were treated the same way.